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TT: Fachverband Tiefe Temperaturen
TT 65: Correlated Electrons: Other Theoretical Topics
TT 65.6: Talk
Friday, March 31, 2023, 11:00–11:15, HSZ 204
Fixed-point annihilation and duality in the SU(2)-symmetric spin-boson model — •Manuel Weber1,2 and Matthias Vojta2 — 1Max-Planck-Institut für Physik komplexer Systeme, Dresden, Germany — 2Institut für Theoretische Physik and Würzburg-Dresden Cluster of Excellence ct.qmat, Technische Universität Dresden, Germany
The annihilation of two intermediate-coupling renormalization-group (RG) fixed points is of interest in diverse fields from statistical mechanics to high-energy physics, but has so far only been studied using perturbative techniques. Using the recently developed wormhole quantum Monte Carlo method, we present high-accuracy results for the SU(2)-symmetric S=1/2 spin-boson (or Bose-Kondo) model. We study the model with a power-law bath spectrum ∝ ωs where, in addition to a critical phase predicted by perturbative RG, a stable strong-coupling phase is present. Using a detailed scaling analysis, we provide direct numerical evidence for the collision and annihilation of two RG fixed points at s∗= 0.6540(2), causing the critical phase to disappear for s<s∗. In particular, we uncover a surprising duality between the two fixed points, corresponding to a reflection symmetry of the RG beta function, which we utilize to make analytical predictions at strong coupling which are in excellent agreement with numerics. Our work makes phenomena of fixed-point annihilation accessible to large-scale simulations, and we comment on the consequences for impurity moments in critical magnets.